Storage Area Networks (SANs) reliably store large amounts of data for an organization. Clusters of storage devices in one location are called SAN islands and communicate among themselves using the Fiber Channel (FC) protocol. Users accessing a SAN typically reside on an Ethernet based Local Area Network (LAN) at another location. Recent advances have led to the creation of Virtual SANs (VSANs) and Virtual LANs (VLANs). VSANs and VLANs remove the physical boundaries of networks and allow a more functional approach, e.g., an engineering department VLAN can be associated with an engineering department VSAN, or an accounting department VLAN can be associated with an accounting department VSAN, regardless of the location of network devices in the VLAN or storage devices in the VSAN. To facilitate communications between the Ethernet based LANs and FC based SANs, and to maintain the reliability associated with the FC protocol, Fiber Channel over Ethernet (FCoE) was developed. FCoE encapsulates FC frames using the Ethernet protocol.
To mediate the conversion from FCoE to FC between the two networks, and vice versa, an intermediate switch is employed, and is sometimes referred to as an FC Forwarder (FCF). When a network device or node accesses an FCF it must login to an FCoE capable VLAN. To learn the correct VLAN to login to, the network device sends a VLAN discovery frame to the FCF. The FCF responds with a list of FCoE enabled VLANs. The network node can now login to the appropriate VLAN and communicate with the desired VSAN.